JP2014111343A - Fusion joint method and fusion joint apparatus of synthetic resin tubes - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fusion joint method and a fusion joint apparatus each capable of avoiding, on an occasion for fusing and joining synthetic resin tubes, the generations of beads on junction inner surfaces.SOLUTION: The provided fusion joint method of synthetic resin tubes is a method for preparing a flexed tube 5 and for joining pipelines by fusing and joining synthetic resin tubes 1 and 2. Terminal portions of the synthetic resin tubes 1 and 2 are heated and melted by a heating plate 31 in a state where a bead generation preventive core 32 capable of absorbing the tolerable inner diameter difference of both synthetic resin tubes is being fitted thereto. The heating plate 31 and bead generation preventive core 32 are removed simultaneously with the completion of melting. A bead presser 4 inducing the contact of both terminal portions of the synthetic resin tubes 1 and 2 while being simultaneously contacted with the inner circumferential surfaces of the latter upon the diametric expansion thereof is inserted therein. The bead presser 4 is subsequently expanded diametrically while both of the terminal portions are simultaneously pressed so as to avoid the generation of beads on the inner surface of the junction. A fusion joint apparatus is also provided.

Description

  The present invention relates to a fusion bonding method and a fusion bonding apparatus for preventing generation of beads on the inner surfaces of the bonded synthetic resin pipes at the time of fusion bonding of two synthetic resin pipes.

  As shown in FIGS. 9A and 9B, in the method of fusing the synthetic resin pipes, the molten resin protrudes from the inner surfaces of the fused portions of the synthetic resin pipes 1 and 2 to generate large beads 13. In the pressure pipe, the beads 13 that protrude from the inner surface of the pipe cause an increase in the pressure loss of the fluid. In a waste liquid drain pipe for chemicals or the like, the waste liquid accumulates on the beads 13 and loses its function as a drain pipe. In transport pipes for foods and medicines, bacteria such as bacteria are generated in the protruding beads 13, causing a deterioration in the quality of the foods and medicines. A method for solving these problems has been proposed as follows.

  There are two types of methods including a similar technique in which the beads 13 are not generated on the inner surface of the pipe when the synthetic resin pipes 1 and 2 are fused.

  In the first type, the end of the tube is heated by radiant heat, the tube is held by the outer peripheral support ring and moved closer to press both tubes, and at the same time, the hollow body already inserted in the tube is expanded to expand the inner periphery A method of supporting and preventing bead formation on the inner surface. For example, it is disclosed in Patent Document 1.

  In the second type, a pipe end is melted in a state where a core composed of a plurality of divided pieces is fitted on the inner surface of the pipe, thereby preventing bead generation on the inner face of the pipe at the time of melting, and then the core is left in the pipe. As it is, a method of preventing the occurrence of beads in the pipe by disassembling the core consisting of the divided pieces in the pipe after joining both ends of the pipe butted and joining them. For example, it is disclosed in Patent Document 2.

Japanese Patent Laid-Open No. 1-110127 JP-A-4-321894

  However, the first type of background art allows beads to also form on the inner surface of the tube while heating the end of the tube without contact. When the hollow body is expanded after the heating is completed, the bead formed during the heating sticks thinly on the inner surface of the tube.

On the other hand, the second type heats the tube with the inner core of the tube fitted therein, so that no bead is generated on the inner surface of the tube. However, since the core does not have a structure capable of absorbing the inner diameter dimensional error of the synthetic resin tube, the variation in the inner diameter size of the synthetic resin tube cannot be absorbed. Therefore, it is not suitable for fusion bonding of pipes having a large inner diameter or more with a large inner diameter.
The object of the present invention, which was created in view of the above circumstances, is to provide a synthetic resin pipe fusion-bonding method and fusion that can prevent the occurrence of beads on the inner surface of a synthetic resin pipe having an inner diameter error. A joining apparatus is provided.

In the method in which the ends of the two synthetic resin pipes are heated and melted with a heating plate, and then the ends are butt-welded,
A step of inserting a bead generation preventing core having a heat insulating property that can be elastically deformed into an end inner surface of the synthetic resin tube in advance;
A step of heating and melting the end of the synthetic resin tube with the heating plate in a state where the bead generation preventing core is fitted;
Simultaneously with the completion of melting, removing the heating plate, removing the bead generation prevention core,
A step of bringing a bead holding device in contact with the inner peripheral surface by expanding the diameter of the two synthetic resin tubes into contact with each other, and placing the bead holding device inside the two synthetic resin tubes;
Pressing the two synthetic resin pipes in close contact with each other, integrating them, and simultaneously expanding the diameter of the bead presser;
A method for fusion-bonding synthetic resin pipes, comprising the step of taking out the bead holding device by reducing the diameter from the integrated synthetic resin pipe.

  Further, in the present invention, in the production of a bent tube having a desired angle between the two synthetic resin tubes, the ends of the synthetic resin tubes cut to ½ of the angle are fused and joined together. A fusion splicing method characterized by manufacturing.

  Further, the present invention is the fusion bonding method, wherein the bead generation preventing core is held by a core holding member of a heating device provided with the heating plate.

  Further, the present invention is a fusion bonding method characterized by fitting directly into an end portion of the synthetic resin tube, heating with the heating plate, removing after completion of heating, and performing fusion bonding.

  Further, the present invention is characterized in that in the step of heating and melting the end portion of the synthetic resin tube with the heating plate, the end portion of the synthetic resin tube is contact-heated or non-contact heated with the heating plate. Joining method.

In addition, the present invention is an apparatus in which the ends of the two synthetic resin tubes are heated and melted by the heating plate, and then the ends are butted and fusion bonded.
A core holding member having an annular groove for fitting the bead generation prevention core is fixed at the center of the heating plate, and the bead generation prevention core is made of an elastomer, and the inner diameter of the bead generation prevention core and the annular shape are A tube end heating device in which a gap is provided between the outer diameters of the grooves;
A bead holding device is provided which is inserted at the same time when the melted pipe ends of the two synthetic resin pipes are brought into contact with each other, presses the pipe ends and simultaneously expands in diameter and comes into contact with the inner peripheral surface. A fusion splicing device.

  Further, the present invention is a fusion bonding apparatus characterized in that a heat insulating member is sandwiched between the heating plate and the core holding member.

  Further, the present invention is the fusion bonding apparatus characterized in that the material for the bead generation preventing core is a heat-resistant and heat-insulating elastomer.

  The present invention is also a fusion bonding apparatus characterized in that an air layer is provided between the bead generation preventing core and the heating plate.

  According to the present invention, it is possible to prevent occurrence of beads on the inner surface of the pipe in the fusion bonding of two synthetic resin pipes having a relatively large inner diameter tolerance.

Schematic of butt fusion bonding apparatus of the present invention Schematic of the non-contact heat fusion bonding apparatus of the present invention Fusion splicing process 1 (a) The process in which two synthetic resin pipes cut to ½ the bending angle face the heating apparatus (b) The pipe ends of the two synthetic resin pipes are connected to the heating apparatus. (C) The step of removing the two synthetic resin tubes from the heating device (d) The step of lightly contacting the two synthetic resin tube ends Fusion splicing step 2 (e) Step of inserting a bead presser device that expands the diameter into two contacted synthetic resin pipes and contacts the inner peripheral surface (f) At the same time as expanding the diameter of the bead presser device, Futaki (G) The process in which the two pressed pipes are completely fused and the bead presser is reduced in diameter and removed. An embodiment in which a heat insulating member is provided between the core holding member and the heating plate in the fusion apparatus of the present invention. In the fusion apparatus according to the present invention, the pipe end is non-contact heating by a straight joint of synthetic resin pipes, a heat insulating member is provided between the core holding member and the heating plate, and air is provided between the bead generation preventing core and the heating plate. Example with layer Example 2 A bead presser that expands in diameter and contacts the inner peripheral surface Other Examples in the Fusion Bonding Step (a) A step of setting a bead generation preventing core at the tube end at the cut tube end (b) A step of heating the tube end with a heating plate Internal bead generation without conventional bead processing (a) Production of bent pipe by butt fusion, internal bead generation (b) Straight pipe butt fusion, internal bead generation Status The standard inner diameter d1 and the longitudinal inner diameter d2 at the butt-welded joint surface of the nominal outer diameter 90 (θ =) 45 ° bent pipe

  An example of the fusion bonding method and fusion bonding apparatus of the present invention for solving the above-described problems is shown in FIGS. FIG. 9 shows an example of fusion bonding in which a conventional bead is generated. FIG. 10 shows the standard inner diameter d1 and the longitudinal inner diameter d2 of the joint when the (θ =) 45 ° bent tube 5 is manufactured.

  First, the minimum and maximum inner diameter dimensions and ellipticity of the synthetic resin pipe are shown in Table 1, and the standard inner diameter and longitudinal inner diameter of the cut surface when the bent pipe 5 is manufactured are shown in Table 2.

Table 1 shows the minimum and maximum inner diameter dimensions and ellipticity of the synthetic resin pipe defined in ISO3126.
The inner diameter difference between the minimum and maximum at the nominal outer diameter 90 is 2.6 mm, and the nominal inner diameter 315 is 7.9 mm. The ellipticity is 1.8 mm at a nominal outer diameter 90.

The bent tube is manufactured by fusing the two synthetic resin tube ends 1 and 2 cut to ½ of the desired bend angle θ to produce a bend tube having the desired angle θ. Can do.
When the desired angle is ½, in two cut synthetic resin tubes, the standard inner diameter d1 and the longitudinal inner diameter d2 of one tube 1 coincide with the standard inner diameter d1 and the longitudinal inner diameter d2 of the other tube 2. To do. If the angle is not ½ of the desired angle, the longitudinal inner diameter d2 of the cut sections of the synthetic resin tubes 1 and 2 will not match, and it will not be possible to produce the bent tube by fusing.

Table 2 shows the standard inner diameter d1 and the longitudinal inner diameter d2 of the fusion bonded surface at the time of manufacturing the bent pipe and the difference between them.

  Taking the nominal outer diameter 90 as an example, from Table 1, the inner diameter difference between the minimum and maximum of the tube is 2.6 mm, and the ellipticity is 1.8 mm. Further, from Table 2, when the (θ =) 45 ° bent tube 5 is manufactured, the standard inner diameter d1 is 71.6 mm and the longitudinal inner diameter d2 is 77.5 mm. A fusion bonding method and a fusion bonding apparatus capable of absorbing these variations in the inner diameter will be described.

  FIG. 1 and FIG. 2 show a situation where two synthetic resin tubes 1 and 2 are heated by a heating plate 31. In the heating device 3, a bead generation preventing core 32 is held by a core holding member 33, which prevents the inner surface of the tube from being melted during heating and generating beads on the inner surface during heating. FIG. 1 shows a method in which the end portions of the synthetic resin tubes 1 and 2 are brought into contact with the heating plate 31 and heated. FIG. 2 shows non-contact heating in which the end portions of the synthetic resin tubes 1 and 2 are not brought into contact.

  When manufacturing the bent tube 5, for example, when manufacturing a 45 ° bent tube with a nominal outer diameter of 90, the outer diameter of the bead generation preventing core 32 is a standard inner diameter (d1 =) 71.6 mm as shown in Table 2. The inner diameter (d2 =) must be 77.5 mm so as to enter the fusion bonded surface.

  Further, in order to absorb the dimensional variation of the inner diameters of the synthetic resin tubes 1 and 2, an inner diameter variation absorbing gap 34 is provided. Even if the synthetic resin tube has the minimum inner diameter shown in Table 1, since the outer diameter of the bead generation preventing core 32 that can be elastically deformed is reduced due to the gap 34, the bead generation preventing core 32 is synthesized. It can be inserted into the resin tube.

The gap 34 preferably has a dimension capable of absorbing the difference between the maximum inner diameter and the minimum inner diameter of the synthetic resin tube. For example, at the nominal outer diameter 90, the gap 34 is desirably 1.3 mm, which is 1/2 of the inner diameter difference (Δd = 2.6 mm) between the maximum and the minimum in Table 1.
In addition, the ellipticity of the synthetic resin tubes 1 and 2 is such that the core 32 is elastically deformed by the insertion of the bead inner diameter holding core 32 so that the core 32 is in close contact with the gap.

3 and 4 will be used to explain the fusing process when manufacturing a bent pipe.
Step (a) Two synthetic resin pipes 1 and 2 cut to ½ of a desired bending angle face the heating device 3. Although there are differences depending on the resin of the synthetic resin tube, in the case of butt fusion, the heating plate 31 is heated to 250 ° C. to 280 ° C. in advance. In the case of non-contact heating, the heating plate 31 is heated to about 400 ° C.

  Step (b) The tube ends of the two synthetic resin tubes 1 and 2 are pushed into the heating device 3, and the tube end is heated by the heating plate 31. A bead generation preventing core 32 capable of absorbing variations in the inner diameter of the synthetic resin tubes 1 and 2 is inserted into the inner surfaces of the synthetic resin tubes 1 and 2. By inserting the bead generation preventing core 32, when the end portions of the synthetic resin tubes 1 and 2 are heated by the heating plate 31, it is possible to prevent the occurrence of beads on the inner surfaces of the synthetic resin tubes 1 and 2. Beads 11 and 21 are generated outside the synthetic resin tubes 1 and 2.

  Step (c) The heating of the tube ends of the two synthetic resin tubes 1 and 2 is completed, and the synthetic resin tubes 1 and 2 are removed from the heating device 3 and heated between the synthetic resin tubes 1 and 2 facing each other. Device 3 is removed.

  Step (d) The cores of the two synthetic resin tubes 1 and 2 are put together and lightly contacted.

  Step (e) The bead presser 4 that expands in diameter and contacts the inner peripheral surface is inserted inside the synthetic resin tubes 1 and 2 that are in light contact.

  Step (f) The bead holding device 4 is expanded in diameter, and at the same time, the two synthetic resin tubes 1 and 2 are strongly pressed to bring the tube end surfaces into close contact with each other. This is maintained until the fusion bonded part is cooled.

  Step (g) The fusion bonding of the two pressed synthetic resin pipes 1 and 2 is completed, and the bead holding device 4 is reduced in diameter, and when it is removed, a bent pipe with no occurrence of beads is completed. .

  FIG. 5 shows an embodiment in which a heat insulating member 35 is inserted between the core holding member 33 and the heating plate 31 of the heating device 3. By inserting the heat insulating member 35, it is possible to prevent the heat of the heating plate 31 from being transmitted to the bead generation preventing core 32. The bead generation preventing core 32 is preferably at a temperature (normal temperature to about 120 ° C.) that does not soften the synthetic resin tube. Examples of the material of the heat insulating member 35 include Teflon (registered trademark), ceramic, SUS304, and glass wool.

  FIG. 6 shows an embodiment of the heating device 3 when the synthetic resin pipes 1 and 2 are fusion-bonded by straight pipes. By non-contact heating, a heat insulating member 35 is inserted between the heating plate 31 and the core holding member 33 of the heating device 3, and an air layer 36 is provided between the bead generation preventing core 32 and the heating plate 31. 32 is prevented from being overheated by the heating plate 31. When the bead generation preventing core 32 is heated, the inner surfaces of the synthetic resin tubes 1 and 2 are heated, and a defect such as a trace of the bead generation preventing core 32 remains on the inner surface of the synthetic resin tube.

The material of the bead generation preventing core 32 is preferably an elastomer having heat resistance and heat insulation. Elastomer originally has heat insulation properties. However, if the contact surface of the elastomer with the hot plate 31 is made uneven or a foamed elastomer or the like is used, heat insulation properties can be increased. By using the heat insulating elastomer, the end portions of the synthetic resin tubes 1 and 2 are prevented from being deprived of heat, and high-quality fusion bonding is possible.
Examples of the elastomer include fluorine rubber, silicon rubber, acrylic rubber, EPDM, and butyl rubber.

FIG. 8 shows a method in which the bead generation preventing core 32 is not held by the core holding member 33 and is manually set on the synthetic resin pipes 1 and 2 that are cut directly. This method is optimal when the number of bent pipes to be manufactured is small.
Step (a) The bead generation preventing core 32 is set manually.
Step (b) Heating with the heating plate 31.
The post-process is the same as in FIG. However, in FIG. 3C, the bead generation preventing core 32 is manually removed.

  FIG. 9 shows the bent pipe 6 in which the beads 13 are generated on the inner surface and the straight joint pipe 7 in which the beads 13 are generated on the inner surface without performing the conventional bead treatment. In both cases, beads 13 are generated on the inner surface of the joint.

As a first embodiment of the bead presser 4 that expands the diameter and contacts the inner peripheral surface, a hollow body is shown in FIGS. 1, 2, 3, 4, 5, and 6. FIG. . Other shapes of hollow bodies are also conceivable. The hollow body at the time of manufacturing the bent pipe may be a hollow body that matches the shape of the bent pipe to be manufactured at the time of expansion.
The air pressure injected into the hollow body is preferably ² to 3 kgf / cm ² .

  The material of the hollow body is a heat-resistant elastomer, and is preferably reinforced with fibers or the like so as not to break when air pressure is applied to the hollow body. The elastomer material is preferably fluorine rubber, silicon rubber, acrylic rubber, EPDM, NBR, butyl rubber, urethane rubber, or the like.

FIG. 7 shows a second embodiment of the bead presser device 4 that mechanically expands the diameter and contacts the inner peripheral surface instead of the expanding hollow body. When the diameter-enlarged core 37 having a conical outer peripheral surface is moved in the X direction (axial direction), the inner peripheral surface contact member 38 is expanded in the Y direction (radial direction). The inner peripheral surface expanded member 38 is an elastomer having high heat resistance, and the material of the elastomer is preferably fluorine rubber, silicon rubber, acrylic rubber, EPDM, NBR, butyl rubber, urethane rubber or the like.
The bead presser 4 that expands the diameter and contacts the inner peripheral surface can be considered other than the example shown here.

  Examples of the synthetic resin tube applicable to the present invention include polyethylene, polypropylene, and polyvinylidene fluoride.

This method is effective when the bead generation is regarded as a problem on the inner surfaces of the fused portions of the two synthetic resin tubes having a large inner diameter dimensional error in the method of fusing the synthetic resin tubes.
Effective for fusion bonding of small-diameter pressure tubes. The molten bead that protrudes from the inner surface of the pipe causes an increase in pressure loss of the fluid in the pipe. This is particularly effective for fusion bonding of small diameter pipes.
Effective for chemical wastewater drain pipes. The waste liquid accumulates and the function as a drain pipe is lost. It is effective for fusion bonding of transportation pipes for food and pharmaceuticals. In the food and pharmaceutical fields, various bacteria such as bacteria are generated in the protruding portion, causing a reduction in product quality. It is effective for fusion bonding to solve these problems.

DESCRIPTION OF SYMBOLS 1 Synthetic resin pipe 11 Bead 12 which generate | occur | produced on the exterior of the synthetic resin pipe 1 with a heating plate Bead 13 which generate | occur | produced on the exterior of the synthetic resin pipes 1 and 2 by fusion | melting Bead which generate | occur | produced inside the synthetic resin pipes 1 and 2 by fusion | melting 2 Synthetic resin tube 21 Bead 3 generated outside of synthetic resin tube 2 by heating plate Heating device 31 Heating plate 32 Bead generation preventing core 33 Core holding member 34 Clearance 35 Heat insulating member 36 Air layer 37 Expanded core 38 Inner peripheral surface contact Member 4 Bead holding device 5 Bent tube 6 Bent tube with bead generated on the inner surface 7 Straight joint tube with bead generated on the inner surface

Claims (9)

In the method in which the ends of the two synthetic resin pipes are heated and melted with a heating plate, and then the ends are butt-welded,
A step of inserting a bead generation preventing core having a heat insulating property that can be elastically deformed into an end inner surface of the synthetic resin tube in advance;
A step of heating and melting the end of the synthetic resin tube with the heating plate in a state where the bead generation preventing core is fitted;
Simultaneously with the completion of melting, removing the heating plate, removing the bead generation prevention core,
A step of bringing a bead holding device in contact with the inner peripheral surface by expanding the diameter of the two synthetic resin tubes into contact with each other, and placing the bead holding device inside the two synthetic resin tubes;
Pressing the two synthetic resin pipes in close contact with each other, integrating them, and simultaneously expanding the diameter of the bead presser;
A method for fusion-bonding synthetic resin pipes, comprising the step of taking out the bead holding device by reducing the diameter from the integrated synthetic resin pipe.   2. The fusion bonding method according to claim 1, wherein two synthetic resin pipes are produced by bending the synthetic resin pipe ends cut at ½ of the angle to produce a bent pipe having a desired angle. A fusion-bonding method, characterized in that it is manufactured by fusion-bonding.   3. The fusion bonding method according to claim 1, wherein the bead generation preventing core is held by a core holding member of a heating device including the heating plate. Method.   3. The fusion bonding method according to claim 1, wherein the bead generation prevention core is directly fitted into an end portion of the synthetic resin tube, heated by the heating plate, and removed after completion of heating. A fusion bonding method, characterized by performing fusion bonding.   5. The fusion bonding method according to claim 1, wherein in the step of heating and melting the end of the synthetic resin tube with the heating plate, the end of the synthetic resin tube is contacted with the heating plate. A fusion splicing method characterized by heating or non-contact heating. In order to carry out the fusing method according to any one of claims 1 to 3, or 5, the ends of the two synthetic resin tubes are heated and melted with the heating plate, and then the ends are abutted and fused. In the joining device,
A core holding member having an annular groove for fitting the bead generation prevention core is fixed at the center of the heating plate, and the bead generation prevention core is made of an elastomer, and the inner diameter of the bead generation prevention core and the annular shape are A tube end heating device in which a gap is provided between the outer diameters of the grooves;
A bead holding device is provided which is inserted at the same time when the melted pipe ends of the two synthetic resin pipes are brought into contact with each other, presses the pipe ends and simultaneously expands in diameter and comes into contact with the inner peripheral surface. A fusion splicing device.   The fusion bonding apparatus according to claim 6, wherein a heat insulating member is sandwiched between the heating plate and the core holding member.   8. The fusion bonding apparatus according to claim 6, wherein a material of the bead generation preventing core is an elastomer having heat resistance and heat insulation. .   9. The fusion bonding apparatus according to claim 6, wherein an air layer is provided between the bead generation preventing core and the heating plate. 10.

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